Hamilton and the Development of Occupational Medicine
Alice Hamiltons formal investigations into the connection between
occupation and disease began in 1910 when she was appointed by Illinois
Governor Charles Deneen to head a survey on industrial illness in Illinois.
Little was known about industrial toxicology, so the members of the commission
had to figure out what trades to explore and to devise a methodology.
They decided to concentrate on occupational poisons in trades known to
be dangerous. In addition to managing the survey, Hamilton studied lead,
the most widely used industrial poison. Others reported on arsenic, zinc
smelting, brass manufacturing, turpentine, and carbon monoxide.
Hamilton and her assistants visited factories, read hospital records,
and interviewed labor leaders and druggists to uncover instances of lead
poisoning. Hamilton wrote in her autobiography, "I was put on the
trail of new lead trades." She discovered more than seventy industrial
processes in which workers were exposed to lead poisoning. In addition
to the more readily known industries where lead exposure was high, industries
such as painting, enamelware, and pottery, Hamilton found some less obvious
ones, including polishing cut glass and wrapping cigars in "tinfoil,"
actually made from lead.
She proudly relates one example in her autobiography, Exploring the
Dangerous Trades, to demonstrate the difficulty in tracking down instances
of lead poisoning and the unexpected industries where it occurred. In
one hospital she found a Polish worker suffering from colic and double
wrist drop. He said he worked in a sanitary-ware factory, applying enamel
to bathtubs. The existing literature made no mention of lead in the paint
used to make bathtubs and the managers of the factory, after assuring
Hamilton that lead was not used, let her inspect the workroom. Puzzled,
she tracked down the victim who told her she witnessed only the final
touching up of the bathtubs. The real work occurred at another factory
where "enameling means sprinkling a finely ground enamel over a red-hot
tub where it melts and flows over the surface." A specimen a worker
gave her contained as much as 20 percent soluble lead. "Thus I nailed
down the fact," Hamilton wrote, "that sanitary-ware enameling
was a dangerous lead trade in the United States."
The Illinois report on industrial disease proved the connection between
occupation and illness. As a result, the Illinois legislature in 1911
passed an occupational disease law requiring employers to implement safety
procedures limiting workers exposure to dangerous chemicals, to
provide monthly medical examinations for workers in dangerous trades,
and to report illnesses to the Department of Factory Inspection, which
had prosecutorial authority. Hamiltons work in Illinois caught the
attention of Charles Neill, the Commissioner of Labor (the United States
Bureau of Labor was a part of the Department of Commerce until 1913).
Neill asked her to do nationally what she had done in Illinois, first
in the lead trades, then in other poisonous occupations. Hamilton described
the limitations under which she worked: "I had, as a Federal agent,
no right to enter any establishment that must depend on the courtesy
of the employer. I must discover for myself where the plants were, and
the method of investigation to be followed. The time devoted to each survey,
that and all else, was left to my discretion. Nobody would keep tabs on
me, I should not even receive a salary; only when the report was ready
for publication would the government buy it from me at a price to be decided
Hamilton accepted Neills offer "and never went back to the
laboratory." Convinced that she would never be anything but "a
fourth-rate bacteriologist" and that she had "no scientific
imagination," Hamilton never doubted her decision to focus on industrial
toxicology, which she described as "scientific only in part, but
human and practical in great measure." Moreover, the job meant she
could continue to live at Hull-House,
which remained her base even as she traveled the country investigating
the dangerous trades.
Hamilton began her work for the federal government by investigating white
lead, commonly used as a paint pigment. Building on what she learned while
conducting the Illinois survey, Hamilton looked for lead dust and lead
fumes since she was convinced the danger for workers came from breathing
air laden with the toxic chemical, and not from ingesting lead. Already
Hamilton employed the techniques of "shoe-leather epidemiology"
that marked all her probes: the careful and extensive use of hospital
records to demonstrate the connection between specific illnesses and occupations,
and the thorough investigation of factories to learn which industrial
processes used dangerous chemicals. Hamilton could not force her way into
factories, but could only request entry. Few denied her, and once inside
she looked for evidence of lead dust and fumes and inquired about the
degree of sickness.
Hamiltons investigation of lead poisoning occurred before reliable
diagnostic tests existed, so she relied on a self-imposed rigid standard.
"I would not accept a case as positive," she wrote, "unless
there was a clear lead line
a deposit of black lead
sulphide in the cells of the lining of the mouth, usually clearest on
the gum along the margin of the front teeth, and it is caused by the action
of sulphureted hydrogen on the lead in these cells, the sulphureted hydrogen
coming from the decaying of protein in the food in the mouth." This
was the standard she employed as she probed lead poisoning among workers
in smelting, enameling, painting, and printing.
Hamilton was not content to merely reveal the extent of lead poisoning
in American industry. Armed with the information she gathered, Hamilton
personally tried to persuade factory owners and managers to remedy dangerous
conditions. A lifelong dread of conflict made this difficult for Hamilton.
But, perhaps owing to her Victorian upbringing, Hamilton was convinced
that people of goodwill, once aware of the facts, would do the right thing.
She wrote of an instance of this in her autobiography when she confronted
Edward Cornish of the National Lead Company and told him that his workers
were being poisoned. Cornish was "both indignant and incredulous"
at first, but when she presented him with twenty-two cases of severe lead
poisoning he reformed his plants by instituting dust and fume prevention
by techniques never before used. Hamilton also convinced Cornish to employ
doctors to conduct weekly inspections of his workers.
During the First World War Hamilton conducted studies on the dangers of
toxic chemicals in the burgeoning war industries. Because of the need
for explosives, factories sprang up to produce TNT, picric acid, mercury
fulminate, and many other substances. Her reports on the dangers in war
industries led to the adoption of many safety procedures, and she later
claimed, with some irony given her anti-war activism, that the war years
helped make industrial toxicology a respectable field of study. There
was also some irony in her reluctance to overtly protest the war since
she wanted to continue working for the Department of Labor.
Her biographer, Barbara Sicherman writes in Alice Hamilton: A Life
in Letters: "By 1915 Alice Hamilton had become the foremost American
authority on lead poisoning and one of a handful of prominent specialists
in industrial disease." She may not have been the first or the only
person studying occupational medicine, but she was probably its only fulltime
practitioner. So when the Harvard Medical School began a program of industrial
hygiene, Hamilton was the obvious choice for appointment as assistant
professor of industrial medicine. In 1922, she moved to the School of
Public Health, launched that year by Harvard. She accepted the appointment
at Harvard on condition that she teach only one semester a year so that
she could continue her field studies. In 1925, she wrote the first text
in the field, Industrial Poisons in the United States, and in 1934
she published Industrial Toxicology. Over the years, she studied
aniline dye, carbon monoxide, mercury, benzene, and other toxic chemicals,
continuing to issue reports for the Department of Labor on the dangerous
After her retirement in 1935, Hamilton conducted a study of the poisons
used in making viscose rayon. This new industry used two dangerous chemicals:
carbon disulfide, which poisoned the central nervous system and led to
mental disease, loss of vision, and paralysis; and hydrogen sulfide, a
powerful asphyxiating toxin. Hamilton first encountered carbon disulfide
in 1914 when she studied rubber making, and she later reported its use
in the manufacture of viscose rayon. Despite its wide use in Europe, carbon
disulfide received little attention in the United States, but Hamilton
became worried in the 1930s when she received reports of serious illnesses
among viscose rayon workers. She persuaded the Department of Labor to
investigate and to appoint her chief medical consultant. The results of
the study were published in Occupational Poisoning in the Viscose Rayon
Industry. It was Hamiltons last investigation, and she was able
to write in her autobiography that "control of this dangerous trade
was slow in coming but when it came it was astonishingly rapid and complete."
Viscose rayon workers, like thousands of workers in other dangerous trades,
could thank Alice Hamilton for helping to control chemical toxins in the